Electrophoretic displays, such as electronic ink (e-ink) displays (also referred to as electronic paper displays), employ an array of microcapsules filled with charged pigment particles, each microcapsule providing a pixel of a displayed image. Altering the displayed image involves applying an electric field to the microcapsules to alter the color state of each pixel and thus form the image. For example, in a black-and-white electronic paper display, various positive or negative voltages may be applied to the microcapsules to adjust a color or brightness state of each pixel along a grayscale from white to black to achieve the desired image.
In contrast to other types of displays (e.g., Liquid Crystal Displays (LCDs)) which exhibit a more deterministic relationship between applied signal and resultant image, electrophoretic displays exhibit a memory effect. For example, in electronic paper displays the brightness of each pixel not only depends on the currently applied voltage, but also depends on a history of the voltages that have been applied to the pixel. Thus, the applied voltages necessary to reach a particular color state of a particular pixel may vary based on the previously applied voltages and, in some cases, other factors such as temperature. This memory effect creates difficulties for developers attempting to write programs to control the images displayed on electrophoretic displays.